DEEP CASE NITRIDING FOR LARGE GEAR AND PINION SET

NITREX INC. – CHICAGO completed a deep case nitriding treatment for a large gear and pinion set intended for power generation service. The specification called for a nitrided case depth 0.025-0.035” (635-900 µm) on a proprietary steel grade, and Nitrex was able to achieve a final case depth of 0.0318 (800 µm).
“What makes this special is that at case depths of only 0.020″ we already see a deterioration of the nitrided surface as a result of the excessive hardness or white layer or both, even with sufficient control and whatever the nitriding technology. To be able to go this deep and to maintain a relatively thin and ductile white layer is why the customer sought the expertise of Nitrex to fulfill these requirements. The specification also called for a significant lower limit of typical nitriding temperatures, which added to the inherent challenges of special handling and masking parts this big.” says Tom Cooper, General Manager of Nitrex Inc. – Chicago Operations.
The parts were treated in the plant’s new Nitrex Gas Controlled Nitriding Furnace that is capable of processing loads sizes of 62” diameter x 177” long (1.6m x 4.5m) and up to 25,000 pounds. Cooper expects to see an increasing demand for deep case nitriding, particularly for parts that are subject to mechanical loads that require increased fatigue strength and lubricity properties.